2.2.1 Determining the Number of Tape Drives On the Bus
You can install from one to four TZ8x7-series tape drives in a StorageWorks
storage-only cabinet, depending upon the model of the cabinet. See the
installation and user’s guide for your specific cabinet for instructions on the
number and location of tape drives in the cabinet. The tape drives may be
configured on one or more buses, but each tape drive bus should contain only tape
drives. For maximum performance, do not mix tape drives and disk drives on the
same bus.
2.2.2 Determining the Quantities of Adapter and Jumper Cables
CAUTION
Failure to use the 17–03831 adapter cable to connect TZ8x7-series tape
drives to StorageWorks SCSI buses may result in improper system
operation and equipment damage. StorageWorks SCSI buses contain
fault detection signals that could be rendered inoperable if any other
cable arrangement is used. The adapter cable must be installed at the
first tape drive on the bus to prevent improper system operation and
equipment damage.
The number of jumper cables required is one less than the number of tape drives
on the bus. One adapter cable must be used on the first tape drive on the bus to
connect it to the host cable.
2.2.3 Determining the Maximum Host Cable Length
To determine the host cable length, add up the lengths of the adapter cable and
all of the jumper cables and subtract it from the maximum total bus length of 6
meters (19.7 feet). The result is the maximum length of the host cable.
Example 2–1 shows the tape drive SCSI bus length calculation for the bus with
four tape drives shown in Figure 1–1.
Example 2–1 Storage-Only Cabinet Tape Drive SCSI Bus Length Calculation
total number of adapter cables = 1
total adapter cable length = 1 x .2 meters = .2 meters
total number of jumper cables = 3
total jumper cable length = 3 x .5 meters = 1.5 meters
total adapter and jumper cable length = 1.7 meters
Maximum SCSI bus length = 6 meters
Maximum length of SCSI A cable from adapter cable to host
(or DWZZA-AA SCSI Signal Converter) = 6 - 1.7 = 4.3 meters
2.2.4 Choosing the Host Cable
Using the StorageWorks Family Configuration Guide, choose the SCSI A cable
that is nearest in length but less than the length you calculated in Section 2.2.3.
In Example 2–1, for instance, you would choose a BN21H–03, 3-meter cable as
the nearest standard cable.
2–2 Planning and Installing a TZ8x7-Series Tape Drive SCSI Bus
